Gameboy - Powers up but no sound or display

[AndehX]

Hi there, seems like i'm the first person to post here, so I'll get the ball rolling with a very odd issues im having with one of my DMG Gameboys

Ok, it seems to power up fine, but I get nothing on the display, and no sound (meaning its not booting games)
I have confirmed that the screen and speaker are good in a different Gameboy, so the problem lies on the logic board somewhere.
This Gameboy has pretty bad battery corrosion which I have cleaned up, and there appears to be no damage to the board, but I just thought I would mention that.
I replaced the little DC board with a known working one, still nothing.

What kind of things can cause a Gameboy to not boot games? Dead capacitors? If so I can replace those easy enough.

Any advice would be appreciated.